Science

Folks have seen the sun’s corona during a total eclipse: ever since around 1715, when Edmond Halley described it.

Before that, maybe not.

Kepler reported “red flames” around the sun during the October 12, 1605, eclipse. Apparently he thought they might be part of a lunar atmosphere.

The earliest recorded observations are almost a thousand years older: but don’t mention anything like a corona.

Maybe folks before Kepler’s day saw the corona but didn’t mention it, or didn’t notice it, or maybe the corona wasn’t there during that period.

Most scientists accept, and track, our star’s 11-year sunspot cycle. It’s half of a 22-year cycle between two magnetic modes.

Other cycles may or may not exist. I figure most of those questions will get answered when we’ve got more data. That could take some time. The Hallstatt cycle, for example, would be roughly two dozen centuries long.1

Misconceptions

Another “Total Solar Eclipse 2017” page has a list of eclipse-related misconceptions, along with a sort of reality check for each. Some of the odd notions were new to me.2

The first two might come from reasonable warnings that looking straight at the sun is a bad idea.

The sun doesn’t, however, produce “harmful rays” during an eclipse. Not any more so than usual.

At least one person heard or remembered that the “harmful rays” were ultraviolet. That’s electromagnetic radiation with wavelengths between 10 and 400 nanometers. Happily, that individual looked for clarification on a Q and A forum: and got a reasonable answer.

Maybe the “radiation” part sounds scary. But UV is like the electromagnetic radiation we call “light,” only with shorter wavelengths. Earth’s atmosphere stops most of the UV coming from our sun, but not all.

The good news is that UV lets us photosynthesize vitamin D. The not-so-good news is that folks can get exposed to too much UV. That doesn’t mean it’s bad, just that we need to use our brains. We can get too much of anything, even water.

Possibly related to the “harmful rays” notion is the also-bogus warning that pregnant women shouldn’t watch the show.

Food preparation during an eclipse is safe, too. More accurately, it’s as safe then as any other time. Using fuzzy mystery meat is always dubiously-prudent.

Eclipses as harbingers of doom might come from old tales like Korea’s Bulgae, fire dogs from the realm of darkness, sent to eat the sun or moon.

My cultural roots include tales of Fenrir, who chases the sun: a chase that ends at Ragnarök. In another tale, Fenrir’s sons Sköll and Hati Hróðvitnisson finally catch the sun and moon — also at Ragnarök.3

Harbingers of Doom

Actual references to belief that eclipses were seen as harbingers of doom are curiously rare. Maybe it’s because folks can predict them, and have: at least since the Seleucid Empire started falling apart.

Herodotus wrote that Thales predicted an eclipse in 585 BC. Since Herodotus didn’t say exactly how Thales knew, some historians say the prediction didn’t happen. Or happened at another date.

One argument is that Thales couldn’t have predicted the eclipse, since other folks didn’t know how at the time.

I’m more willing to think that Thales may have predicted the eclipse. Or maybe he made a lucky guess. I think it’s at least as likely that records detailing how Thales arrived at his results didn’t survive.

Another possibility is that the account as Herodotus received it — wasn’t entirely accurate. What we don’t know about the past is frustratingly extensive. (March 30, 2017)

Vikings

Comets are another matter.

Quite a few folks in 11th century Europe thought a big comet showing up meant that a kingdom would fall.

Normans were descendants of Vikings who had decided that coastal France was nicer than where they’d been living.

The French king — wisely, I think — graciously granted them permission to stay on the land they’d moved to. That was around 911. The Vikings promptly dropped their Scandinavian language, names, and customs. But not, I think, their attitude.

Another bunch of Vikings, the Rus’, did pretty much the same thing: heading east.

Nestor’s chronicle says that they came to help folks living where Novgorod is now. The locals were having trouble dealing with other Vikings.

Nestor apparently worked for descendants of the Rus’, but my guess is that the locals didn’t do too badly in the long run. We call that part of the world Russia these days, and that’s another topic.

England’s King Edward died in January, 1066. England’s Witenagemot said someone named Harold was king now. Assorted other folks disagreed, and Vikings landed on Scarborough beach, adding their opinion.

Meanwhile, Normans saw the comet and were building an invasion fleet. Maybe they figured that the comet meant a kingdom would fall — which made this an excellent time to take over England. Which they did. (December 11, 2016)

About five and a half centuries later, the Great Comet of 1556 caused quite a stir. But this time the Normans mostly stayed put. Apparently they liked ruling their own island.

They — and most other European rulers — were moving in on folks in other parts of the world by then, and that’s yet another topic.

Where was I? Eclipses, Bulgae, Thales, Vikings, the Great Comet of 1556. Right.

At least some folks called it the Charles V comet. He was emperor of the Holy Roman Empire, an impressive title that still meant something in his day.

We’re told that Charles V saw the comet, said “By this dread sign my fates do summon me,” abdicated, and entered a monastery. Another account says that maybe he quit because of gout.

The Thirty Year’s War started little over six decades later. That killed a lot of folks, arguably made the Enlightenment and French Revolution possible, and that’s yet again another topic. Topics. (August 20, 2017; July 14, 2017; November 6, 2016 )

The first predictions of solar eclipses we’ve got good documentation for are the Saros series. Someone worked that cycle out a bit upwards of two millennia back.4

1. Various Angles

(From Pete Marovich/WCIV/Getty, via BBC News, used w/o permission.)
(“Beachgoers at Isle of Palms, South Carolina: The great fear is that cloud will spoil the show”
(BBC News))

“It is also the first such event since 1918 where the path of darkness traverses both the Pacific and Atlantic coasts, and the first total solar eclipse to make landfall exclusively in the US since independence in 1776….”

ABC News 4 reported that the Isle of Palms county park and municipal parking lot filled to capacity before noon.

Some folks on the beach said they had trouble getting cellular service. The Post and Courier’s Andrew Knapp wrote that folks there saw lightning and clouds, and a bit of the eclipse at one point.

Most news services reported what folks saw and how they reacted as the shadow crossed America. At least one writer managed to find relevant social commentary on this “gods-forsaken age,” and the unseemly expressions of enthusiasm. With, I’m told, a light touch:

I mostly enjoyed seeing how folks were enjoying the show. Like I said, going outside in my part of central Minnesota would have gotten me wet during much of the event.

2. T-Shirts and Science

(From Reuters, via BBC News, used w/o permission.)
(“The US is getting very excited for the eclipse. These T-shirts are being sold in Oregon, because this is the first place that will get to see it!”
(BBC Newsround))

“On Monday 21 August, millions of people will be able to witness one of the most amazing space events that can be seen from the Earth.

“Across the US, lucky space watchers will be treated to an incredible total solar eclipse.

“The last time the US witnessed an eclipse like this was in 1979, so everybody is understandably pretty excited!

“This one is being called the Great American Eclipse 2017….”

The 1979 eclipse started over the Pacific; swept across North America, mostly Canada; and ended over Greenland. It was one of 71 total eclipses during the 20th century.

Since eclipses let us look at the sky near Earth’s sun, scientists generally try to set up equipment where there’s good visibility along the path of totality.

A U.S. Naval Observatory expedition tried, unsuccessfully, to test Einstein’s prediction about gravity bending light during the 1918 eclipse.

Two other expeditions tried again during the 1919 eclipse. They collected data, but nowhere near accurately enough to settle the ‘Einstein or Newton’ question.5

Questions, Answers, and More Questions

The idea that gravity bends light didn’t start with Einstein.

At least two scientists had worked out how much gravity would bend light, based on Newtonian physics.

Henry Cavendish recorded his work in 1784, but didn’t publish.

Georg von Soldner did his work in 1801, and published in 1804.

Natural philosophers had been thinking about light long before Isaac Newton added his corpuscular theory of light in 1704. Some had said light acts like waves, others held something like Newton’s view.

Newton said that an aethereal medium might account for diffraction. That was in 1718. Since then, we’ve learned that the ‘wave’ and ‘particle’ ideas were both correct, sort of: but not quite. We’re currently working our way through quantum mechanics.6

Einstein got Soldner’s value for how much light should be bent, given Newtonian physics, in 1911. In 1915, Einstein noticed that general relativity’s math also shows that light would be bent. But only about half as much as Newtonian physics says it should.

Scientist collected data with the needed precision about five decades after the 1919 eclipse.

We’re currently pretty sure that general relativity fits observed reality. Except where it doesn’t. The last I heard, we’re still figuring out how quantum entanglement works. Getting that answer may tell us why it’s so fast. Or maybe instantaneous.

Either way, I’m pretty sure we’ll uncover a great many other questions in the process. My guess is that we’ll continue fine-tuning our understanding of this universe for as long as it’s around.

That will probably upset folks who get uncomfortable around new ideas.

Others will see keep seeing scientific discoveries as opportunities to admire more of God’s work. (Catechism of the Catholic Church, 283, 341)

3. Awe and “Dark Forces”

(From Joe Burbank/Associated Press, via The Sacramento Bee, used w/o permission.)
(“Florida high school students react to seeing the sun, using their eclipse glasses for the first time during a trial run on Friday, Aug. 18, 2017, for their planned viewing of Monday’s eclipse. Eclipse mania is building and so is demand for the glasses that make it safe to view the first total solar eclipse to cross the U.S. in 99 years.”
(The Sacramento Bee))

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About Brian H. Gill

I'm a sixty-something married guy with six kids, four surviving, in a small central Minnesota town. I mostly write and make digital art. I'm only interested in three things: that which exists within the universe; that which exists beyond; and that which might exist.

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